U.S. patent application number 13/866767 was filed with the patent office on 2013-10-24 for stator for an electric machine having end windings pressed into a housing.
The applicant listed for this patent is Robert Bosch GmbH. Invention is credited to Markus Bahr.
Application Number | 20130278088 13/866767 |
Document ID | / |
Family ID | 49290149 |
Filed Date | 2013-10-24 |
United States Patent
Application |
20130278088 |
Kind Code |
A1 |
Bahr; Markus |
October 24, 2013 |
STATOR FOR AN ELECTRIC MACHINE HAVING END WINDINGS PRESSED INTO A
HOUSING
Abstract
A stator (1) and a method for manufacturing such a stator for an
electric machine. Windings of the stator (1) protrude in the
longitudinal direction beyond a cylindrical stator body (3) in the
form of end windings (17, 19) on end faces (13, 15) of the stator
body (3). In this case, a complementarily designed accommodating
region (31) is provided on a housing (21), with the result that,
when the housing (21) is assembled with the stator body (3), the
windings of the end winding (17) can be pressed. As a result, good
thermal contact can be effected between the end winding (17) and
the housing (21), which is cooled via a cooling apparatus (25), for
example.
Inventors: |
Bahr; Markus; (Waiblingen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Robert Bosch GmbH |
Stuttgart |
|
DE |
|
|
Family ID: |
49290149 |
Appl. No.: |
13/866767 |
Filed: |
April 19, 2013 |
Current U.S.
Class: |
310/52 ;
29/596 |
Current CPC
Class: |
H02K 9/22 20130101; H02K
5/20 20130101; H02K 15/14 20130101; H02K 15/0043 20130101; H02K
15/02 20130101; H02K 9/00 20130101; Y10T 29/49009 20150115; H02K
5/04 20130101 |
Class at
Publication: |
310/52 ;
29/596 |
International
Class: |
H02K 9/00 20060101
H02K009/00; H02K 15/02 20060101 H02K015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 19, 2012 |
DE |
10 2012 206 442.7 |
Claims
1. A stator (1) for an electric machine, comprising: a cylindrical
stator body (3); a housing (21) surrounding the stator body (3);
and a plurality of windings (5); wherein the windings (5) are
arranged so as to run along the stator body (3) and protrude in a
longitudinal direction beyond the stator body (3) in the form of
end windings (17, 19) at end faces (13, 15) of the stator body (3);
and wherein an end region (29) of the housing (21) protrudes in the
longitudinal direction beyond the stator body (3) and a first
accommodating region (31) is formed at the protruding end region
(29) of the housing (21), said accommodating region surrounding a
first of the end windings (17) so as to bear tightly against a
first end face (13) of the stator body (3).
2. The stator according to claim 1, wherein the windings (5) are
pressed, in a region of the end winding (17), in the accommodating
region (31) of the housing (21).
3. The stator according to claim 1, wherein a layer consisting of
an electrically insulating cladding material is arranged on the
accommodating region (31) on a surface directed towards the end
winding (17).
4. The stator according to claim 3, wherein the cladding material
comprises a ceramic matrix material in which metal particles are
embodied.
5. The stator according to claim 3, wherein the cladding material
comprises a material selected from the group consisting of paper,
polymer film, Pertinax, pressboard and polyamide film.
6. The stator according to claim 1, further having an end plate or
a terminating ring (37), wherein the end plate or terminating ring
(37) has a second accommodating region (35), which surrounds a
second of the end windings (19) so as to bear tightly against a
second end face (15) of the stator body (3).
7. The stator according to claim 1, further having an end guard
(39), wherein the end guard (39) has a second accommodating region
(41), which surrounds a second of the end windings (19) so as to
bear tightly against a second end face (15) of the stator body
(3).
8. The stator according to claim 1, wherein the housing (21) is
provided with a cooling device (25) for cooling the stator body (3)
accommodated therein and the end windings (17, 19).
9. A method for manufacturing a stator (3) for an electric machine,
wherein the method comprises: providing a cylindrical stator body
(3); arranging windings (5) along the stator body (3) in such a way
that the windings (5) protrude in the longitudinal direction beyond
the stator body (3) in the form of end windings (17, 19) on end
faces (13, 15) of the stator body (3); providing a housing (21),
which is designed to surround the stator body (3), wherein a first
accommodating region (31) is formed at an end region (29) of the
housing (21), said first accommodating region being designed to
surround a first of the end windings (17) so as to bear tightly
against a first end face (13) of the stator body (3); and
assembling the housing (21) with the stator body (3) in such a way
that the first winding (17) is accommodated in the accommodating
region (31) and is pressed therewith.
10. The method according to claim 9, further comprising: deforming
the first end winding (17) into an outwardly tapering form prior to
the assembly of the housing (21) with the stator body (3).
11. The method according to claim 9, further comprising:
introducing an additional joining part (45) adjacent to the first
accommodating region (31) of the housing (21) and in alignment with
the first accommodating region (31) of the housing (21) prior to
the assembly of the housing (21) with the stator body (3).
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a stator for an electric
machine and to a method for manufacturing such a stator.
[0002] Electric machines are used for a wide variety of purposes
for example in the form of electric motors or generators. In this
case, the electric machine has a stationary stator and a rotor
which rotates relative to this stator. Typically, a large number of
windings of an electrically conductive wire are provided on the
stator in order to form electromagnets with the aid of these
windings, which electromagnets can be used, during operation of the
electric machine, to generate alternating magnetic fields, for
example.
[0003] The windings can be arranged on or in a stator body, wherein
the stator body is generally formed from a magnetizable material,
usually from a metallic material. In this case, the stator body
generally has a cylindrical form, wherein the windings can be
oriented on the stator body in a direction parallel to the mid-axis
of the cylinder or at a slight angle to the mid-axis of the
cylinder.
[0004] At the front and rear ends of the stator body, the windings
in this case protrude beyond the stator body and are usually
deflected into bundles, with the result that so-called end windings
are formed at the end faces of the stator body. While the windings
run in substantially linear fashion and parallel to or at an acute
angle to the mid-axis of the cylindrical stator body in the region
of the stator body, the windings are deflected in the region of the
end windings in such a way that they run at least partially in the
circumferential direction of the cylindrical stator body, wherein
the windings are located outside the stator body in the region of
the end windings and protrude beyond the end faces of said stator
body.
[0005] For this purpose, in conventional electric machines, the
windings arranged on the stator body are first embossed in the
protruding regions and then a fixing band is wrapped around said
windings, which is a complicated procedure. The end winding
produced in this way is generally exposed to the air when the
electric machine is completely assembled, as a result of which the
windings in the region of the end winding can at best be cooled
poorly.
SUMMARY OF THE INVENTION
[0006] Stators for electric machines in accordance with embodiments
of the present invention enable improved cooling of the entire
stator including the regions of the end windings and can also be
simple to manufacture.
[0007] The invention proposes providing a stator for an electric
machine with a cylindrical stator body, a housing surrounding the
stator body and a plurality of windings. In this case, the windings
are preferably arranged so as to run parallel to or at an angle to
a mid-axis of the stator body along the stator body and protrude in
the longitudinal direction beyond the stator body in the form of
end windings at end faces of the stator body. The housing
surrounding the stator body in this case has an end region, which
protrudes in the longitudinal direction beyond the stator body. In
this case, a first accommodating region is intended to be formed on
the protruding end region of the housing, said first accommodating
region surrounding a first of the end windings so as to bear
tightly against a first end face of the stator body.
[0008] In addition, a method for manufacturing a stator for an
electric machine is proposed. The method comprises the following
method steps, preferably in the order given: (a) providing a
cylindrical stator body; (b) arranging windings along the stator
body in such a way that the windings protrude in the longitudinal
direction beyond the stator body in the form of end windings at end
faces of the stator body; (c) providing a housing, which is
designed to surround the stator body, wherein a first accommodating
region is formed on an end region of the housing, which first
accommodating region is designed to surround a first of the end
windings so as to bear tightly against a first end face of the
stator body; and (d) assembling the housing with the stator body in
such a way that the first end winding is accommodated in the
accommodating region and is pressed therewith.
[0009] Embodiments of the stator according to the invention or of
the manufacturing method according to the invention for such a
stator can be considered, inter alia, as being based on the
following concepts and insights:
[0010] In electric machines, a considerable quantity of lost heat
is usually released during operation. Therefore, the electric
machine and in particular the stator thereof needs to be cooled
during operation. For this purpose, in the case of conventional
electric machines, for example, a heat sink of a cooling apparatus
can be arranged so as to bear tightly against the solid stator body
or can be integrated therein. In general, the stator body consists
of a metallic material which has a good thermal conductivity, with
the result that the wire windings arranged on the stator body emit
the heat released therein to the stator body effectively and can
pass this heat on to the cooling apparatus via said stator
body.
[0011] However, in the region of the end windings, i.e. outside the
end faces of the stator body, the wire windings are no longer in
direct thermal contact with the stator body. In the case of
conventional electric machines, the end windings are merely
surrounded by air and can only be cooled by this air, which means
that the windings in the region of the end windings can be heated
to high temperatures.
[0012] It is now proposed to develop the housing surrounding the
stator body in such a way that at least one first accommodating
region is formed on the housing, which first accommodating region,
in the assembled state of the electric machine, surrounds an end
winding which protrudes beyond an end face of the stator body in
such a way as to bear tightly against said end winding. Owing to
the fact that the housing bears tightly against the end winding,
intensive thermal contact between the end winding and the housing
can be provided, with the result that heat generated in the end
winding can be dissipated effectively to the housing.
[0013] In this case, the housing itself can consist of a material
with good thermal conductivity, such as a metal, for example, or at
least have regions with good thermal conductivity, with the result
that the heat absorbed by the end winding in the accommodating
region can be dissipated effectively and preferably passed toward a
cooled region of the electric machine.
[0014] For example, the housing can be provided with a cooling
device for cooling the stator body accommodated therein and the end
windings. For this purpose, the housing can have, for example, one
or more channels integrated in the housing, through which channels
a coolant can be passed.
[0015] The accommodating region provided in the end region of the
housing can be formed integrally with the rest of the housing. For
example, overhangs, projections, depressions, cutouts, etc. can be
formed on or in the housing in such a way that a geometry of an
accommodating region formed thereby is substantially complementary
to a geometry of the end winding to be accommodated in the
accommodating region. The end winding can in this case initially
still have relatively large dimensions prior to fitting of the
stator since the windings in the region of the end winding have not
yet been pressed with one another so as to bear tightly against one
another. Owing to the geometric configuration of the accommodating
region provided on the housing, a force can be exerted on the
windings running in the end winding by the accommodating region
during assembly of the housing with the stator body in such a way
that the windings are pressed at the point where they come into
contact with the accommodating region of the housing in the region
of the end winding.
[0016] Such a pressing operation can be used to bring the windings
into tight contact both with one another and with the surface of
the accommodating region, with the result that interspaces between
the windings or between windings and the accommodating region are
minimized. Such a pressing operation can thus result in good
thermal contact both between the individual windings and between
the windings and the accommodating region and therefore with the
housing.
[0017] The individual windings of the stator are generally
electrically insulated from one another by a thin surrounding
insulating layer. Should this insulating layer be damaged, for
example during the manufacturing process, individual windings can
have exposed metallic regions. In the event of such exposed regions
coming into contact with electrically conductive material of the
housing in an accommodating region, there is thus the risk of a
local short circuit or a local connection to ground.
[0018] In order to avoid this, the invention proposes arranging a
layer consisting of electrically insulating cladding material on
the accommodating region on a surface directed toward the end
winding. This layer can be very thin, for example thinner than 0.1
mm, since the layer is merely intended to ensure electrical
insulation and is not intended to perform any substantial
mechanical tasks. The thickness of the layer can in this case be
selected such that the electrical insulation function of the layer
is ensured to a sufficient extent and nevertheless sufficiently
effective heat transfer from those windings of the end winding
which bear against the layer through the insulating layer to the
metallic material of the housing can take place.
[0019] In an advantageous configuration, the electrically
insulating cladding material can be formed with the aid of a
ceramic matrix material, in which metal particles, for example
silver or copper particles, are embedded. The ceramic-like matrix
material is in this case electrically insulating and the metal
particles are embedded with such a density that, in general, no
electrical contact is produced between adjacent metal particles,
with the result that the cladding material overall has an
electrically insulating effect. Nevertheless, such a cladding
material can have comparatively good thermal conductivity owing to
the embedded metal particles.
[0020] The layered cladding material can in this case be arranged
as a separate insert on the surface of the housing in the
accommodating region. Alternatively, the surface of the
accommodating region can be coated or sprayed with such a cladding
material, or the cladding material can be applied to this surface
in another way.
[0021] In an alternative configuration, the cladding material can
be formed, for example, with the aid of paper, a polymer film,
Pertinax, pressboard or a polyamide film. All of these materials
can firstly have an electrically insulating effect and secondly
allow sufficient thermal conductivity through the material
layer.
[0022] While the end winding protruding beyond the stator body at
one end at the end face there can be in thermal contact with the
accommodating region on the housing, for manufacturing reasons it
may be difficult to bring the end winding which protrudes beyond
the end face at the opposite end into thermal contact with the
surrounding housing as well.
[0023] Therefore, a further configuration proposes providing the
stator additionally with an end plate or a terminating ring, which
are each fixed, for example, to the housing of the stator by virtue
of being pressed therewith. Then, a second accommodating region can
be formed on such an end plate or terminating ring, which second
accommodating region can surround the second end winding so as to
bear tightly against said second end winding. Therefore, heat can
thus be passed from the second end winding via the accommodating
region of the end plate or terminating ring and the end plate or
terminating ring itself onto the housing and possibly a cooling
apparatus provided there.
[0024] An end plate is in this case understood to mean a cover for
the housing of the electric machine which protects the machine
interior from touching contact, for example, and can accommodate
the bearings of the shaft ends of an armature accommodated in the
electric machine. In order to ensure an air gap between a stator
and the armature of the electric machine which is as uniform as
possible, the end plate is in this case usually fitted very
precisely into the stator housing. In this case, the end plate can
act as an A end plate, i.e. be arranged on an output side of the
electric machine and bear a fixed bearing or can be formed as a B
end plate and be arranged on the fan side of the electric
machine.
[0025] Alternatively, a terminating ring can be provided on the
stator, which terminating ring in turn has a second accommodating
region, which can surround the second opposite end winding so as to
bear tightly against said end winding. A terminating ring can in
this case be understood to mean an additional ring which produces a
connection between the end winding and the housing.
[0026] As a further alternative, an end guard can be provided on
the stator. Such an end guard can be joined to the cylindrical
region of the housing on an end side of the stator in order to
close said stator. In turn, a second accommodating region can be
formed on the end guard, which second accommodating region can
surround the second opposite end winding so as to bear tightly
against said second end winding.
[0027] The second accommodating region which is provided on the end
plate or the terminating ring or the end guard can have a similar
design to the first accommodating region provided on the housing,
i.e. its dimensions can be matched, for example, to the dimensions
of the second end winding to be pressed and a layer consisting of
electrically insulating cladding material can be provided on its
surface.
[0028] In order to be able to achieve a tightly bearing contact
between the end windings and the respective accommodating regions
during manufacture of the stator, the housing, on one side, and the
stator body or the end plate or the end guard, on the other side,
can be assembled with a sufficiently high force that the turns of
the end winding which protrude on the end side of the stator body
are deformed by the respective accommodating region and are pressed
so as to be in close contact with one another.
[0029] In order in this case to reduce the risk of damage to the
windings in the end windings, the end winding can be deformed into
an outwardly tapering form prior to assembly of the housing with
the stator body. Owing to such an outwardly tapering form, it is
possible to avoid a situation in which, for example, individual
windings protrude to too great an extent out of the end winding and
are damaged during assembly of the housing with the stator
body.
[0030] As an alternative or in addition, prior to the assembly of
the housing with the stator body, an additional joining part can be
arranged adjacent to the first accommodating region of the housing
and in alignment therewith. With the aid of such a joining part
arranged with alignment, it is likewise possible to avoid a
situation in which individual windings of an end winding are
damaged during assembly of the housing with the stator body.
[0031] It is noted that possible features and advantages of
embodiments of the invention are described herein sometimes with
reference to a stator according to the invention and sometimes with
reference to a method according to the invention for manufacturing
a stator. A person skilled in the art will be aware that features
of individual embodiments can be combined or replaced
advantageously and in particular can be transferred from the stator
to the method, or vice verse, in order to thus arrive at further
embodiments and possibly synergy effects.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Embodiments of the invention will be described below with
reference to the attached drawings, with neither the description
nor the drawings being intended to restrict the invention in any
way.
[0033] FIG. 1 shows a perspective view of a stator for an electric
machine without an associated housing.
[0034] FIG. 2 shows a longitudinal section through a stator in
accordance with an embodiment of the present invention.
[0035] FIG. 3 shows a longitudinal section through a stator in
accordance with an alternative embodiment of the present
invention.
[0036] FIG. 4 illustrates a sequence of a method for manufacturing
a stator in accordance with an embodiment of the present
invention.
[0037] FIG. 5 illustrates a method step for deforming an end
winding for a manufacturing method in accordance with a further
embodiment of the present invention.
[0038] FIG. 6 illustrates another method step for a manufacturing
method in accordance with a further embodiment of the present
invention.
[0039] The figures are merely schematic and are not true to scale.
Identical reference symbols are used in the figures for identical
or functionally identical features.
DETAILED DESCRIPTION
[0040] FIG. 1 shows a perspective illustration of an internal
region of a stator for an electric machine. In the case of the
stator 1, a large number of windings 5 are inserted or drawn into a
cylindrical stator body 3. The windings 5 in this case run through
channels running in the longitudinal direction of the stator body 3
or cutouts in the metallic stator body 3. In this case, the
windings 5 can be arranged parallel to a mid-axis 7 of the stator
body 3 in order to form a non-skewed stator. As is shown in FIG. 1,
the windings can also run at an angle to the parallel of the
mid-axis 7, however, in order to form a skewed stator.
[0041] Ends 9 of the windings 5 can be led out of the stator stack
and provided with connections 11 for each of the electrical phases
to be applied to the windings.
[0042] As illustrated in FIG. 1, in each case a bundle of a
plurality of winding wires runs through one of the channels
provided in the stator body 3. At the ends of the stator body 3,
i.e. at the end faces 13, 15 thereof, the windings 5 protrude
beyond the end faces 13, 15 of the stator body 3 and are bent back
from one direction of extent substantially parallel to the mid-axis
7 towards a direction of extent substantially transverse thereto
and along the circumference of the cylindrical stator body 3 at the
end faces 13, 15 thereof. In this case, a first and a second end
winding 17, 19 are formed adjacent to the end faces 13, 15 of the
stator body 3.
[0043] In order to simplify the illustration, only the windings 5
which protrude beyond the end faces 13, 15 are illustrated
schematically in FIG. 1, with three of the winding bundles being
indicated and the rest of the end winding 17 constructed from
windings 5 being illustrated only schematically as a ring.
[0044] FIGS. 2 to 6 illustrate longitudinal sections through
subregions of the stator 3 illustrated in FIG. 1, i.e. sections
parallel to the mid-axis 7.
[0045] FIG. 2 shows an embodiment of a stator 1 in which a
cylindrical stator body 3 is pressed into a surrounding housing 21.
The housing 21 is in this case likewise cylindrical at its inner
circumference and is matched to the outer circumference of the
stator body 3, with the result that the housing 21 bears against
the stator body 3 with a tight press fit and therefore with good
thermal contact. The housing 21 is provided with a cooling channel
23, which is part of a cooling device 25 for cooling the stator
body 3. A rotor 27 is accommodated within the stator body 3.
[0046] The housing 21 protrudes in the longitudinal direction both
beyond the first end face 13 and beyond the second end face 15 of
the stator body 3. A first accommodating region 31 is in this case
formed in an end region 29 protruding beyond the end face 13. In
this case, a projection 33 is formed integrally on the housing 21.
The projection 33 is formed in such a way that the accommodating
region 31 has a geometry which is substantially complementary to
the first end winding 17 to be accommodated therein in a pressed
state. An inwardly directed surface of the accommodating region 31
thus bears tightly against the windings accommodated therein of the
first end winding 17 in the assembled state of the stator. As a
result, good heat transfer between the windings of the first end
winding 17 and the housing 21 bearing against said end winding in
the accommodating region 31 can be achieved.
[0047] In order to reduce the risk of a short circuit or a
connection to ground of possibly damaged windings within the end
winding 17 via the conductive material of the housing 21 in the
accommodating region 31, the inwardly directed surface of the
accommodating region 31 can be provided with an electrically
insulating layer (not illustrated).
[0048] As an alternative to an integral design of the accommodating
region 31 or the projection 33 on the housing 21, the accommodating
region 31 can also be formed by a separate component part, which is
fixed on the housing 21. Such a separate component part can consist
of a material which is electrically insulating but has sufficient
thermal conductivity, for example.
[0049] At the second end face 15, the second end winding 19
protruding there can be pressed with the aid of a second
accommodating region 35, which is formed on an additional
terminating ring 37 to be pressed with the housing 21.
Alternatively, the second accommodating region 35 could also be
integrally formed on an end plate of the electric machine (not
illustrated).
[0050] In the alternative embodiment of a rotor 1 illustrated in
FIG. 3, an end guard 39 is provided on the side of the second end
winding 19 instead of the terminating ring 37. A second
accommodating region 41 with a form which is complementary to the
second end winding 19 to be pressed is formed on this end guard 39.
By virtue of such a further variant, an additional working step in
the manufacture, for example for introducing the terminating ring
37, and a corresponding separate part for the construction of the
electric machine can be avoided.
[0051] With reference to FIGS. 4 to 6, steps in a method for
manufacturing a stator in accordance with an embodiment of the
present invention will now be described.
[0052] As illustrated in FIG. 4(a), first a cylindrical stator body
3 is provided; in this case windings are arranged on the stator
body 3 in such a way that they protrude beyond end faces 13, 15 of
the stator body 3 in the form of end windings 17, 19.
[0053] Then, a housing 21 is assembled with the stator 3 (step
4(b)). In this case, the first end winding 17 is pressed so as to
bear tightly by the accommodating region 31 formed on the housing
21, and the individual wires of the windings are thus fixed and
brought into good thermal contact both with one another and with
the housing 21 (step 4(c)).
[0054] A second joining part, for example in the form of an end
guard 37 or an end guard 39, is then joined with the housing 21 on
an opposite side (step 4(d)). In this case, the windings of the
second end winding 19 are pressed so as to bear tightly against one
another (step 4(e)).
[0055] In order to reduce the risk of the windings of an end
winding 17, 19 to be pressed being damaged during joining or
pressing of the housing 21 with the stator body 3 or with the
additional joining part 37, 41, said end windings can be deformed
to give an outwardly tapering form prior to the assembly, as is
illustrated in FIG. 5. For this purpose, the end winding 17
protruding beyond the stator body 3 is pressed into a funnel-shaped
die 43, for example. Alternatively, the end winding 17 could be
pressed into an appropriately sized tapering form, for example with
the aid of two clamping jaws.
[0056] As a further measure for reducing the risk of damage to the
windings of end windings during assembly of the component parts of
the stator, an additional joining part 45 can be arranged prior to
the assembly of the housing 21 with the stator 3 in such a way that
the joining part 45 directly adjoins the accommodating region 31 of
the housing 21 and aligns a surface 47 of the joining part 45 with
a surface 49 of the housing 21 in the accommodating region 31.
[0057] In the case of the stator 1 proposed herein, efficient
cooling can be achieved even in the region of the end winding 17
owing to the tightly bearing pressing of the accommodating region
31 provided on the housing 21, for example with the end winding 17
protruding beyond the stator body 3. In addition, the pressing of
the end windings 17, 19 with correspondingly complementarily
designed accommodating regions 31, 35, 41 enables simple and
reliable manufacture of such a stator 1.
* * * * *